The control valves are destined for the Manifa field development in Saudi Arabia, which will eventually produce 900,000 barrels a day of heavy crude oil. Weld overlay cladding has helped Severn Glocon overcome the prohibitive cost of casting globe valves in a corrosion resistant alloy, which is the conventional method of protecting them from sour, corrosive gases such as hydrogen sulfide.

For Arc Energy, the contract involved cladding the inside wetted areas of twenty-four globe valves ranging from 6-inch to 24-inch diameters with a 4mm thick coating of a corrosion resistant nickel based alloy. The largest of the valves, four 24-inch units weighing 12 tonnes each, were among the first to be clad on two new Rotating Head welding machines, which Arc Energy installed late last year at a cost of £500,000 in order to extend the size and scope of the equipment the company can handle.

Commenting for Arc Energy, managing director Alan Robinson says the vast weight and size of the 24-inch valves would have presented a serious handling challenge for conventional welding workstations, which apply overlay cladding by moving components around a fixed welding torch.

Explaining the significance of the automated Rotating Head machines, he says they are designed to manipulate the welding head around the fixed globe valve, positioning the head to apply the overlay accurately to the complex cast geometries.

He adds that Arc Energy worked with Severn Glocon engineers to develop a geometry that was suitable for cladding, and the new machines certainly justified their investment by effectively applying the essential protective coating in areas that would usually be considered difficult to clad.

Arc Energy’s project management of the cladding contract also involved the production of bespoke tooling to handle the different sizes of the valves and meet the special access requirements. All twenty-four valves were produced to a strict delivery schedule, with Arc Energy effectively utilizing their resources to meet cladding deadlines. Arc Energy also undertook heat treatment after the cladding process, as well as pre- and post-NDT testing.

Summing up, Severn Glocon sales director Ron Baker comments: “The close working relationship with Arc Energy helps to ensure that our high-integrity valves meet even the most demanding needs of our customers, whilst still being cost-effective.”